Kinetics of the labeling reactions of thymine, cytosine and uracil with osmium tetroxide bipyridine
The electroactive complex osmium tetroxide bipyridine holds great promise as a covalent label for biosensor applications regarding nucleic acids and protein detection. Labeling can easily be performed in the laboratory. Until now, almost only DNA species have been investigated using this label. Thymine (which occurs exclusively in DNA) is known to react much faster than cytosine and uracil. In order to explore the possibilities to modify and detect also RNA species in a timely fashion, we have investigated the kinetics of reactions of osmium tetroxide bipyridine with the pyrimidine bases in the micromolar concentration range at different temperatures by means of spectrophotometry. Results were confirmed using voltammetric detection for the determination of labeled oligonucleotides. The modification reaction can be easily completed at room temperature within 7 h, even in case of cytosine and uracil. At 60 °C, 3 h are sufficient for complete modification of all pyrimidine bases that are found in natural nucleic acids. These findings will be important for future biosensor applications with RNA species as target molecules.
KeywordsOsmium tetroxide bipyridine Pyrimidine bases UV spectrophotometry Reaction kinetics Activation energy
This project has been supported financially by the Deutsche Forschungsgemeinschaft (DFG, FL 384/4-2, 7-1, 8-1).
- 2.Lukasova E, Jelen F, Palecek E (1982) Electrochemistry of osmium nucleic-acid complexes—a probe for single-stranded and distorted double-stranded regions in DNA. Gen Physiol Biophys 1:53–70Google Scholar
- 4.Lukasova E, Vojtiskova M, Jelen F, Sticzay T, Palecek E (1984) Osmium-induced alteration in DNA-structure. Gen Physiol Biophys 3:175–191Google Scholar
- 12.Jelen F, Karlovsky P, Makaturova E, Pecinka P, Palecek E (1991) Osmium-tetroxide reactivity of DNA bases in nucleotide sequencing and probing of DNA-structure. Gen Physiol Biophys 10:461–473Google Scholar
- 23.Moore WJ (1990) Grundlagen der Physikalischen Chemie. Walter de Gruyter Verlag, Berlin, p 373Google Scholar